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vasopressin)

Water deprivation test (dehydration [est or concentration

test). Indicated for diagnosing diabetes insipidus (01).

Normally, if water is withheld, ADH levels rise to help

increase water reabsorption in the kidneys. During the

test, the patient is deprived of Au ids, and serial measurements of urine osmolality are taken. Normally,

ADH secretion causes a change in urine osmolality, but

E.NDOCRINE. SYSTEM

663

Hormone(s)

Test Description

with 01, the osmolality remains unchanged. While

the patient is being deprived of water, vasopressin

may be administered to help delineate whether the

DI is caused by piruitary or renal dysfunction.

Water loading test. Indicated for diagnosing syndrome

of inappropriate anridiureric hormone (SIADH).

During the tesr, the patienr ingests 20-25 mUkg of

fluid, with hourly serum and urine osmolaliry levels

being measured for 4 hrs. Normally, with water

ingesrion, the plasma and urine osmolality should

decrease, and urine output should increase. With

SIADH, there is little or no change in these values.

Source: Data from LM Malarkey, ME McMorrow (cds). Nurse's Manual of Laboratory

Tes[s .and Diagnostic Procedures. Philadelphia: Saunders, 2000;580-584, 552-555,

613-614,616-619.

Pih,itary Disorders

Dysfunction of the pituitary-hypothalamic system generally results

from hyper- or hyposecretion of tropic hormones. Hypersecretion of

pituitary hormones (hyperpituitarism) is most commonly due to benign

anterior pituitary tumors. Hyposecretion of pituitary hormones (pituitary insufficiency) can result from pituitary disease, diseases affecting the hypothalamus or surrounding structures, or disturbance of blood

Aow around the hypothalamus and pituitary.'2,13

Hyperpituitarism

The overproduction of the pituirary hormones GH, ACTH, and

antidiuretic hormone (ADH) is discussed below.

Growth Hormone Ouerproductioll

The most common presentation of excessive GH secretion is acromegaly in adults or gigantism in children. Excessive GH secretion has been linked primarily to anterior pituitary adenomas and not necessarily from excessive hypothalamic stimulation of the pituitary.13

Signs and symptoms of acromegaly include the following1•13:

• Enlargement of hands and feet, coarse facial features with furrowed brows

• Oligomenorrhea or amenorrhea in women

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AClITE CARE HANDBOOK FOR PHYSICAL THERAPISTS

• Paresthesia of hands, carpal tunnel syndrome

• Sweating

• Headaches

• lmpotence in men

• Diabetes mellitus

•

Hypertension

•

Joint pains, osteoarthritis

Management of acromegaly may consist of the following:

transphenoid surgical resection of anterior pituitary adenoma (treatment of choice), GH suppression with somatostatin and its analogs (octreotide), or with dopamine agonists and external irradiation as a

last resorr.14

Clinical Tip

Given the multisystem effects in patients with acromegaly, activity progression should proceed cautiously,

with a focus on energy conservation and joint protection techniques.

Adrenocorticotropic Hormone Overproduction

An increase in ACTH production by the pituitary gland results in

increased levels of serum cortisol, which is a glucocorticoid secreted

by the adrenal glands. Glucocorticoids are involved with carbohydrate, protein, and fat metabolism; therefore, excess cortisol levels affect these cellular processes. Any clinical syndrome that results in

glucocorticoid excess is called Cushing's syndrome. Cushillg's disease,

however, is specific to pituitary lesions that cause bilateral adrenal

hyperplasia and is not discussed in this chapter.' Pituitary hypersecretion of ACTH occurs in approximately 70% of the patients with Cushing's syndrome. The hypersecretion of ACTH is mainly from

pituitary adenomas or microadenomas.6

Signs and symptoms of Cushing's syndrome include the following"., '.13:

• Truncal obesity with thin extremities

•

Redness and rounding of the face (moon face)

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665

• Easy bruising, thinning of the skin, and presence of striae and

darker pigmentation

• Hirsutism, oligomenorrhea, or amenorrhea

• Hypertension

• Osteoporosis (radiographically confirmed)

• Proximal muscle weakness

• Backache

• Glucose intolerance

Management of Cushing's syndrome may consist of any of the following: surgical resection of pituitary lesion, radiation or chemotherapy for the lesion, or medical management with steroidogenic inhibitors (ketoconazole, mitotane, etomidate, metyrapone, and aminoglutethimide) or neuromodulators of ACfH release (valproic acid, bromocriptine, and cyproheptadine). Surgical resection of the adrenal

glands is a last-resort measure.14

Clinical Tip

Management of weakness, myopathy, pain, edema, and

osteoporosis should be the focus of physical therapy intervention and be complementary to the medical management of the patient. Blood pressure changes during activity should be monitored, given the possibility of hypertension.

Caution should also be taken to avoid bruising during

mobility. Refer to Diabetes Mellitus for further activity

considerations.

Antidiuretic Hormone Overproduction

The syndrome of inappropriate secretion of ADH (SIADH) is a condition of fluid and electrolyte imbalance resulting in hyponatremia (reduced sodium levels) from excessive water reabsorption. In this

condition, ADH is secreted from the posterior pituitary when it

should be inhibited.